Guess the HP!
Post up a dyno sheet.
Not the graph, but a sheet with some data on it.
487hp from that combo is way low.
On the dyno here:
Flat top 446, untouched ootb RPM’s, xs282s cam, 1.5’s, SD/850, 1-7/8 x 3 headers……makes right at 500hp.
My first thought is…….it appears to be a vacuum secondary carb.
Maybe it’s not fully opening on the rear.
If the dyno shop has a decent DP on hand……. Try that.